A designer can rely on many tools and skills to tackle specific UX design tasks and effectively limit subjectivity when evaluating solutions. Also, a senior designer — or design lead, or UX manager, etc. — is expected to contribute to the overall functioning of the team to provide a “tailwind” and increase the odds of success.
When HBO brought streaming development into house it meant building out a team of 40+ designers with complimentary skills — UX, IX, VX, microcopy creation, technical writing, and research — to create experiences with content loops, recommendations, and contextual editorial input to appeal to users as individuals. Additionally, as the team grew processes needed to evolve to fit changing demands.